Development Of Crystal Malt And Its Application In Beer Brewing

Malt is an important raw material in beer production.The beer made of different kinds of malt has different flavor,color and taste.Crystal malt is an important specialty malt,and its endosperm is glassy and crystalline.It give beer a variety of flavors and unique taste.In this paper,the main characteristic volatile flavor compounds of crystal malt were determined by comparing and analyzing the volatile flavor compounds in commercially crystal malt.By optimizing the production technology of crystal malt,the high-quality crystal malt was prepared and its influence on beer brewing process and quality was studied.The physicochemical indicators of 20 kinds of commercial crystal malt were measured and analyzed.It was found that the chroma of crystal malt was between 100 to 300 EBC generally,and the anhydrous extraction rate was between 72.0%to 77.0%.The volatile flavor compounds of 20 crystal malts were determined by gas chromatography-mass spectrometry,and 14 main characteristic volatile flavor compounds in the crystal malt were identified by principal component analysis.They were isobutyraldehyde,2-methylbutyraldehyde,isovaleraldehyde,isodihydrolavandulal,benzaldehyde,phenylacetaldehyde,4-methyl-2-phenyl-2-pentenal,cocal,hexanal,furfural,5-methyl furfural,2,3-pentanedione,1-octen-3-ol and furfuryl alcohol.Compared with imported crystal malt,the crystalline endosperm of domestic crystal malt was not complete and full,the total concentration of volatile flavor compounds was only 417.97?g·L^-1,which was only 49.03%of imported crystal malt.Through the single factor experiment and central composite group design experiments,the preparation process of crystal malt was determined as follows:barley?Metcarlfe?was selected as the raw material.During the second steeping,CaCl₂ and KCl were added with the concentration of 30 mg·L^-1 and 70 mg·L^-1.The germination time was 72h,when the green malt had higher amylase activity.The prepared green malt was subjected to protein rest for 2h at 60°C,and then saccharified for 2 h under the condition of 71.1°C and pH 3.36.Finally,the pre-saccharified green malt was roasted,the moisture was eliminated at 100°C maintain50 minutes,and then the temperature was increased to 120°C maintain 30 minutes.The obtained crystal malt has the chroma of 271 EBC,the anhydrous extraction rate was 77.7%,the crystallization rate was 98%,and the total content of volatile flavor compounds was1265.31?g·L^-1,which was 48.39%and 162.94%higher than imported crystal malt(852.51?g·L^-1)and domestic crystal malt(491.95?g·L^-1),respectively.The homemade crystal malt and imported crystal malt were brewed respectively.After adding crystal malt,the flavor of beer was improved,and the content of esters increased significantly,reaching 2011.70?g·L^-1.As the amount of crystal malt added increases,the flavor of beer became more and more intense.However,adding too much crystal malt affected the growth of yeast,brought bitterness to beer and affected the overall sensory of beer.The suitable addition amount of crystal malt was about 10%.The contents of esters,acids and alcohols in the beer obtained by the 200 L pilot brewing with homemade crystal malt were 5734.49 g·L^-1,1806.55 g·L^-1 and 1778.98 g·L^-1,respectively,Compared with the beer obtained by the 200 L pilot brewing of imported crystal malt,it was 62.96%,39.46%and63.24%higher respectively,and the sensory evaluation score was higher,which was 84 points,and the sensory evaluation score of the beer obtained by the 200 L pilot brewing of imported crystal malt was 74 points.